title: Comparison of integrated whole-body [11C]choline PET/MR with PET/CT in patients with prostate cancer.
abstract: OBJECTIVE
  To evaluate the performance of conventional [(11)C]choline PET/CT in comparison to that of simultaneous whole-body PET/MR.
  
  
  METHODS
  The study population comprised 32 patients with prostate cancer who underwent a single-injection dual-imaging protocol with PET/CT and subsequent PET/MR. PET/CT scans were performed applying standard clinical protocols (5 min after injection of 793 ± 69 MBq [(11)C]choline, 3 min per bed position, intravenous contrast agent). Subsequently (52 ± 15 min after injection) PET/MR was performed (4 min per bed position). PET images were reconstructed iteratively (OSEM 3D), scatter and attenuation correction of emission data and regional allocation of [(11)C]choline foci were performed using CT data for PET/CT and segmented Dixon MR, T1 and T2 sequences for PET/MR. Image quality of the respective PET scans and PET alignment with the respective morphological imaging modality were compared using a four point scale (0-3). Furthermore, number, location and conspicuity of the detected lesions were evaluated. SUVs for suspicious lesions, lung, liver, spleen, vertebral bone and muscle were compared.
  
  
  RESULTS
  Overall 80 lesions were scored visually in 29 of the 32 patients. There was no significant difference between the two PET scans concerning number or conspicuity of the detected lesions (p not significant). PET/MR with T1 and T2 sequences performed better than PET/CT in anatomical allocation of lesions (2.87 ± 0.3 vs. 2.72 ± 0.5; p = 0.005). The quality of PET/CT images (2.97 ± 0.2) was better than that of the respective PET scan of the PET/MR (2.69 ± 0.5; p = 0.007). Overall the maximum and mean lesional SUVs exhibited high correlations between PET/CT and PET/MR (ρ = 0.87 and ρ = 0.86, respectively; both p < 0.001).
  
  
  CONCLUSIONS
  Despite a substantially later imaging time-point, the performance of simultaneous PET/MR was comparable to that of PET/CT in detecting lesions with increased [(11)C]choline uptake in patients with prostate cancer. Anatomical allocation of lesions was better with simultaneous PET/MR than with PET/CT, especially in the bone and pelvis. These promising findings suggest that [(11)C]choline PET/MR might have a diagnostic benefit compared to PET/CT in patients with prostate cancer, and now needs to be further evaluated in prospective trials.
authors.affiliation: Department of Nuclear Medicine, Technische Universität München, Ismaningerstr. 22, 81675, Munich, Germany, msouvatz@yahoo.de.
authors.forename: Michael
authors.initials: M
authors.lastname: Souvatzoglou
authors.forename: Matthias
authors.initials: M
authors.lastname: Eiber
authors.forename: Toshiki
authors.initials: T
authors.lastname: Takei
authors.forename: Sebastian
authors.initials: S
authors.lastname: Fürst
authors.forename: Tobias
authors.initials: T
authors.lastname: Maurer
authors.forename: Florian
authors.initials: F
authors.lastname: Gaertner
authors.forename: Hans
authors.initials: H
authors.lastname: Geinitz
authors.forename: Alexander
authors.initials: A
authors.lastname: Drzezga
authors.forename: Sibylle
authors.initials: S
authors.lastname: Ziegler
authors.forename: Stephan G
authors.initials: SG
authors.lastname: Nekolla
authors.forename: Ernst J
authors.initials: EJ
authors.lastname: Rummeny
authors.forename: Markus
authors.initials: M
authors.lastname: Schwaiger
authors.forename: Ambros J
authors.initials: AJ
authors.lastname: Beer
mesh_terms: D000368:Aged; D002250:Carbon Radioisotopes; D002794:Choline; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D011471:Prostatic Neoplasms / Q000175:diagnosis / Q000000981:diagnostic imaging*; D019275:Radiopharmaceuticals; D014057:Tomography, X-Ray Computed; D051598:Whole Body Imaging
chemical_list: D002250:Carbon Radioisotopes; D019275:Radiopharmaceuticals; D002794:Choline